Mix together the lemon juice and sugar in a pitcher or a mixing bowl until the sugar is dissolved. Stir in the water.
Chill the homemade lemonade for at least 1 hour.
Then add 1 cup of the lemonade and 2 cups of the ice cream to a blender.
Blend until smooth. Pour into a cup and serve with lemon slices (optional).
Notes
You can use bottled lemon juice for this recipe. If using bottled juice, increase the amount to 1 ½ cups of lemon juice. This drink is best served immediately. You can store it in the freezer covered for up to 1-2 days.